Method of using an ice cream machine

ABSTRACT

An ice cream machine for cooling liquid ice cream into frozen ice cream includes an evaporator having a cylindrical cooling tank and an auxiliary tank. The auxiliary tank ensures that the cylindrical cooling tank is flooded with liquid refrigerant during normal operation. The flooding of the cylindrical cooling tank provides more efficient and even cooling in an interior cooling chamber. The more efficient cooling allows the ice cream machine to utilize a smaller compressor, thereby reducing the cost and energy consumption of the ice cream machine. The auxiliary tank can be a coil of tubing or a cylindrical container positioned above the cylindrical cooling tank.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS FIELD OF THE INVENTION

[0001] The present invention relates to refrigeration or coolingsystems. More particularly, the present invention relates to an icecream machine having an auxiliary evaporator tank.

BACKGROUND OF THE INVENTION

[0002] Ice cream machines as well as other systems for cooling orfreezing food stuffs, condiments, or other materials, typically includean evaporator situated proximate the material being chilled. Forexample, in ice cream machines, liquid ice cream is typically insertedin a freezing chamber adjacent the evaporator and is removed from thefreezing chamber as solid or semi-solid ice cream. The evaporatorremoves heat from the freezing chamber as a liquid refrigerant such asFREON®, ammonia, HP62, 502 or other liquid having a low boiling pointchanges to vapor in response to the heat from the liquid ice cream.Typically, the evaporator is partially filled with vapor as the liquidrefrigerant boils (e.g., becomes vapor) in the evaporator.

[0003] Since most heat transfer occurs when the liquid refrigerant ischanged to vapor, the partially filled evaporator is less efficient thana flooded evaporator (e.g., an evaporator filled entirely with liquidrefrigerant). The partially filled evaporator also tends to unevenlycool the ice cream because the parts of the evaporator which are filledwith vapor are not able to cool as effectively as the parts of theevaporator filled with liquid. Further, prior art ice cream machines aredisadvantageous because the pressure does not remain constant in theevaporator due to the accumulation of vapor. The inefficienciesresulting from the partially filled evaporator require the ice creammachine to use a larger, more expensive, and less energy efficientcondenser or pump.

[0004] Thus, there is a need for an ice cream machine which utilizes aflooded evaporator. There is also a need for an evaporator whichprovides even cooling in the freezing chamber.

SUMMARY OF THE INVENTION

[0005] The present invention relates to an ice cream machine including acylindrical evaporator having a refrigerant input and a refrigerantoutput, an evaporator reservoir having a reservoir input and a reservoiroutput, a compressor having a compressor input and a compressor output,and a condenser having a condenser input coupled to the compressoroutput and a condenser output coupled to the refrigerant input. Thecylindrical evaporator has an interior surface defining a coolingchamber which has an ice cream input and an ice cream output. Thereservoir input is coupled to the refrigerant output. The evaporatorreservoir is located above the cylindrical evaporator with respect togravity. The compressor input is coupled to the reservoir output. Therefrigerant travels from the condenser through the cylindricalevaporator and the evaporator reservoir to the compressor. Therefrigerant boils from its liquid state to a vapor state. Therefrigerant accumulates as a vapor in the evaporator reservoir, therebyproviding superior cooling in the cylindrical evaporator.

[0006] The present invention also relates to a cooling system forcooling a food stuff including a compressor, and evaporator in the shapeof a hollow cylinder, and an auxiliary evaporator means. The evaporatorhas a refrigerant input and a refrigerant output and contains the foodstuff. The auxiliary evaporator means is positioned above the evaporatorwith respect to gravity and receives liquid refrigerant from therefrigerant output of the evaporator. The auxiliary evaporator meansprovides the vapor refrigerant to the compressor. The compressorreceives the vapor refrigerant and provides the liquid refrigerant tothe evaporator. Superior cooling of the food stuff in the evaporator isobtained by completely filling the evaporator with the liquidrefrigerant. The auxiliary evaporator means cause the evaporator to becompletely filled with the liquid refrigerant.

[0007] The present invention also relates to an improved ice creamfreezing machine including a tubular evaporator, a compressor, and acondenser. The tubular evaporator has a refrigerant input at a bottomside of the evaporator, a refrigerant output at the top side of theevaporator, and an interior surface defining an interior coolingchamber. The interior cooling chamber has an ice cream input and an icecream output. The compressor has a compressor input and a compressoroutput. The condenser has a condenser input coupled to the compressoroutput and a condenser output coupled to the refrigerant input. Theimprovement includes an evaporator reservoir having a reservoir inputcoupled to the refrigerant output and a reservoir output coupled to thecompressor input. The evaporator reservoir is located above thecylindrical evaporator with respect to gravity. A refrigerant travelsfrom the condenser through the cylindrical evaporator and the evaporatorreservoir to the compressor. The refrigerant is a liquid in thecylindrical evaporator. The refrigerant accumulates as a vapor in theevaporator reservoir thereby, providing superior cooling in the coolingchamber.

[0008] In one aspect of the present invention, an auxiliary tank ispositioned above (e.g., located higher than) the evaporator. Theauxiliary tank may be a coil of copper tubing or a container such as acylindrical or spherical reservoir. The auxiliary tank ensures that thecylindrical evaporator is flooded with liquid refrigerant such as FREONor HP62. According to another aspect of the present invention, theevaporator is a cylindrical evaporator having an interior coolingchamber. Liquid ice cream is inserted into the interior cooling chamberand exits the cooling chamber as solid ice cream. Alternatively, yogurt,condiments, or other food stuffs may be chilled or frozen in the coolingchamber.

[0009] Preferably, low pressure liquid refrigerant enters thecylindrical evaporator at a bottom side and exits the cylindricalevaporator at a top side. The low pressure liquid refrigerant boils andaccumulates as vapor in the auxiliary tank. The refrigerant returns tothe compressor as low pressure vapor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention will hereafter be described with reference to theaccompanying drawings, wherein like reference numerals denote likeelements, and:

[0011]FIG. 1 is a schematic diagram illustrating an ice cream machine inaccordance with an exemplary embodiment of the present invention;

[0012]FIG. 2 is a more detailed side view schematic diagram of thecylindrical cooling tank and auxiliary tank illustrated in FIG. 1; and

[0013]FIG. 3 is a cross-sectional view of the cylindrical cooling tankillustrated in FIG. 2 at line 3-3.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT OF THEPRESENT INVENTION

[0014] A cooling system or ice cream machine 10 is diagrammaticallyshown in FIG. 1. Ice cream machine 10 includes an evaporator 20, anexpansion valve 22, a solenoid valve 24, a sight glass 26, a filter 28,a condenser 30, a compressor 32, an accumulator 34, and a valve 36.Evaporator 20 includes a cylindrical cooling tank 38 and an auxiliarytank 48.

[0015] Cylindrical cooling tank 38 includes a refrigerant input 40, arefrigerant output 42, a liquid ice cream input 44, and a solid icecream output 46. Auxiliary tank 48 includes a liquid refrigerant input52 and a vapor refrigerant output 54. Cylindrical cooling tank 38includes a cooling chamber 56 defined by an interior surface or wall 58of tank 38.

[0016] Auxiliary tank 48 is positioned above with respect to gravity orover cylindrical cooling tank 38. Additionally, liquid refrigerant input52 is located above refrigerant output 42, and refrigerant input 40 oftank 38 is located beneath refrigerant output 42 of tank 38. Vaporrefrigerant output 54 of tank 48 is located above liquid refrigerantinput 52 of tank 48.

[0017] With reference to FIGS. 2 and 3, cylindrical cooling tank 58 ismanufactured from an outside tube 59 having an inside diameter of 4.75inches, an outside diameter of 5 inches, and a length of 27.75 inches,and an inner tube 57 having an inside diameter of 3.75 inches, anoutside diameter of 3.875 inches, and a length of 30 inches. Preferably,wall 58 is 0.125 inches thick. The volume of interior cooling chamber 56is approximately 331 cubic inches. The volume of an evaporator chamber61 between outer tube 59 and inner tube 57 has a volume of approximately165.1 cubic inches. Auxiliary tank 48 is preferably a piece of tubing orother container having a length of 7 inches, a width of 2 inches, and adepth of 4 inches. The approximate volume of tank 48 is 56 cubic inches.

[0018] The operation of ice cream machine 10 is described below withreference to FIGS. 1-3. Compressor 32 provides high pressure vaporrefrigerant to condenser 30. Ice cream machine 10 may utilize arefrigerant such as ammonia, FREON, HP62, or other substance having alow boiling point. The type of refrigerant is not a limiting factor withrespect to the present invention.

[0019] Condenser 30 provides high pressure liquid refrigerant throughfilter 28, sight glass 26 and solenoid valve 24 to expansion valve 22.Expansion valve 22 provides low pressure liquid refrigerant toevaporator 20. More particularly, low pressure liquid refrigerant isprovided to refrigerant input 40 of cylindrical cooling tank 38. The lowpressure liquid refrigerant in cooling tank 38 is boiled due to the heatfrom cooling chamber 56, to form low pressure vapor refrigerant whichaccumulates in auxiliary tank 48. The low pressure liquid refrigerant incylindrical cooling tank 38 preferably cools or freezes the liquid icecream from input 44 in cooling chamber 56. Although, ice cream isdisclosed, other food stuffs, substances, or condiments may be utilizedin machine 10.

[0020] More particularly, the warmer liquid ice cream with respect tothe liquid refrigerant provided to liquid ice cream input 44 is cooledand provided as frozen ice cream at ice cream output 46 as the lowpressure liquid refrigerant is transferred from liquid to vapor. The lowpressure vapor refrigerant collects via auxiliary tank 48. Preferably,system 10 is provided with enough liquid refrigerant so that all ofcylindrical cooling tank 38 is filled and auxiliary tank 48 istwo-thirds to one-half filled with liquid refrigerant during normaloperation of ice cream machine 10.

[0021] The low pressure vapor refrigerant in tank 48 travels from vaporrefrigerant output 54 through valve 36 and accumulator 34 to compressor32. Compressor 32 changes the low pressure vapor refrigerant to highpressure vapor refrigerant and provides the high pressure vaporrefrigerant to condenser 30. Condenser 30 changes the high pressurevapor refrigerant to high pressure liquid refrigerant which is providedto valve 22.

[0022] The flooding of tank 38 advantageously provides even cooling asliquid ice cream travels from ice cream input 44 to ice cream output 46because the temperature and pressure of the low pressure liquidrefrigerant in cylindrical cooling tank 38 is maintained constant.Therefore, the ice cream in cooling chamber 56 is chilled evenlywherever it is vertically located within cooling chamber 56. Prior artcooling tanks tended to chill the ice cream unevenly near the top of theevaporator because liquid refrigerant was only located on the bottom ofthe evaporator.

[0023] The use of such an advantageous evaporator 20 allows system 10 tobe designed with a relatively small compressor 32. The small size ofcompressor 32 makes ice cream machine 10 less expensive and more energyefficient. Preferably, auxiliary tank 48 may be a coil of copper tubinglocated above cylindrical cooling tank 38. Preferably, auxiliary tank 48is a tank located above cylindrical cooling tank 38 such as acylindrical or spherical tank, reservoir, can, or other container.Cylindrical cooling tank 38 preferably has almost three times the volumeof auxiliary tank 48.

[0024] It is understood that, while the detailed drawings and specificexamples given to describe the preferred exemplary embodiment of thepresent invention, they are for the purpose of illustration only. Theapparatus of the invention is not limited to the precise details andconditions disclosed. For example, although food stuffs and ice creamare mentioned, the invention may be utilized in a variety ofrefrigeration or cooling systems. Further, single lines for carryingliquid refrigerant can represent multiple tubes. Additionally, althougha particular valve, accumulator, compressor, condenser and filterconfiguration is shown, the advantageous evaporator 20 may be utilizedin other cooling systems. Various changes can be made to the detailsdisclosed without departing from the spirit of the invention which isdefined by the following claims.

What is claimed is:
 1. An ice cream machine, comprising: a cylindricalevaporator having a refrigerant input, and a refrigerant output, thecylindrical evaporator having an interior surface defining a coolingchamber, the cooling chamber having an ice cream input and an ice creamoutput; an evaporator reservoir having a reservoir input and a reservoiroutput, the reservoir input being coupled to the refrigerant output, theevaporator reservoir being located above the cylindrical evaporator withrespect to gravity; a compressor having a compressor input coupled tothe reservoir output and a compressor output; and a condenser having acondenser input coupled to the compressor output and a condenser outputcoupled to the refrigerant input, whereby a refrigerant travels from thecondenser through the cylindrical evaporator and the evaporatorreservoir to the compressor, the refrigerant being a liquid in thecylindrical evaporator, the refrigerant accumulating as a vapor in theevaporator reservoir, thereby providing superior cooling in thecylindrical evaporator.
 2. The ice cream machine of claim 1 wherein theevaporator reservoir is a length of copper tubing significantly longerthan a distance from the compressor to the evaporator reservoir.
 3. Theice cream machine of claim 1 wherein the evaporator reservoir is a tank.4. The ice cream machine of claim 3 wherein the tank has a volume atleast 0.33 times a volume of the cylindrical evaporator.
 5. The icecream machine of claim 1 wherein liquid ice cream is provided to the icecream input and frozen ice cream is provided by the ice cream output. 6.The ice cream machine of claim 1 wherein the evaporator reservoir istwo-thirds filled with the liquid.
 7. A cooling system for cooling afoodstuff, the cooling system comprising: compressor; an evaporator inthe shape of a hollow cylinder, the evaporator having a refrigerantinput and a refrigerant output, the evaporator containing the foodstuff;and an auxiliary evaporator means, positioned above the evaporator withrespect to gravity, for receiving a liquid refrigerant from therefrigerant input of the evaporator and providing a vapor refrigerant tothe compressor, the compressor receiving the vapor refrigerant andproviding the liquid refrigerant to the evaporator, whereby superiorcooling of the foodstuff in the evaporator is attained by completelyfilling the evaporator with the liquid refrigerant, the auxiliaryevaporator means causing the evaporator to be completely filled with theliquid refrigerant.
 8. The cooling system of claim 7 wherein theauxiliary evaporator means is a length of copper tubing significantlylonger than a distance from the compressor to the evaporator.
 9. Thecooling system of claim 8 wherein the copper tubing is wound in a coilabove the evaporator.
 10. The cooling system of claim 7 wherein theauxiliary evaporator means is a cylindrical tank.
 11. The cooling systemof claim 10 wherein the tank has a volume at least 0.33 times a volumeof the evaporator.
 12. The cooling system of claim 7 wherein thefoodstuff is frozen in the evaporator.
 13. The cooling system of claim 7wherein the auxiliary evaporator means is two-thirds filled with theliquid refrigerant.
 14. The cooling system of claim 12 wherein thefoodstuff is ice cream.
 15. The cooling system of claim 12 wherein thefoodstuff is yogurt.
 16. An improved ice cream freezing machineincluding a tubular evaporator having a refrigerant input at a bottomside of the evaporator, and a refrigerant output at a top side of theevaporator, the tubular evaporator having an interior surface definingan interior cooling chamber, and the cooling chamber having an ice creaminput and an ice cream output, a compressor having a compressor inputand a compressor output, and a condenser having a condenser inputcoupled to the compressor output and a condenser output coupled to therefrigerant input, the improvement comprising: an evaporator reservoirhaving a reservoir input coupled to the refrigerant output, and areservoir output coupled to the compressor input, the evaporatorreservoir being located above the cylindrical evaporator with respect togravity, whereby a refrigerant travels from the condenser through thecylindrical evaporator and the evaporator reservoir to the compressor,the refrigerant being a liquid in the cylindrical evaporator, therefrigerant accumulating as a vapor in the evaporator reservoir, therebyproviding superior cooling in the cooling chamber.
 17. The improved icecream machine of claim 16 wherein the evaporator reservoir is a lengthof tubing substantially longer than the distance between the evaporatorand the compressor.
 18. The improved ice cream machine of claim 17wherein the tubing is coiled.
 19. The improved ice cream machine ofclaim 16 wherein the refrigerant contains FREON™.
 20. The improved icecream machine of claim 16 wherein the auxiliary resevoir is acylindrical tank.